Emerald

History

The word emerald comes from Latin smaragdus , deformation of the Persian word zamarat . As for other metals and invaluable stones, myths and legends mix with historical reality when one speaks about emerald. One evokes of it already the presence with Babylon, with being used as currency of exchange. At the ancient period of Egypt, close to the Red Sea, was emerald mines, which one manufactured jewels for large empire. These mines of Djebel Zabarah, redécouvertes in 1816 by the French explorer Frederic Cailliaud, were wrongly called mines of Cléopâtre. They were already exhausted, but they contained probably only gems of poor quality.

In antiquity, authors like Théophraste, Hérodote or Pline Old the mention the presence of emeralds, and describe sometimes statues, even columns or obelisks cut in this stone. It is known now that they were not true emeralds. At these moved back times, other stones with the green reflections could easily give the exchange, and there existed already imitations, in particular out of glass. On the other hand, it is conceivable that statuettes were cut in blocks of minerals in a rough state, of less quality.

At the time Roman, one evokes an emerald blade used like optical instrument by the emperor Néron, who would have been used for himself about it to correct his myopia when it looked at the combat of gladiators. At that time, one knew mainly a mine in Europe, that of Habachtal in Austria. Discovered by Celtic tribes , it was also exploited by the Romans.

At the 16th century, the Spaniards discover in South America of new layers, mainly in Colombia. The mine of Chivor will be worked starting from 1545 and that of Muzo in 1560.

In India, the stone of “Large Moghol”, discovered in 1695, weighs 217,80 Carat S and measurement approximately 10 cm. It carries religious inscriptions. It was bought for 2,2 million dollars by an anonymity.

Until the beginning of the 20th century, one also called “Eastern emerald” a radically different stone: the green Corundum, whose composition is connected with that of the Rubis and the Saphir.

Most beautiful emeralds

The Devonshire , a rough crystal of a constant green of 1384 carats, is perhaps the most famous emerald. Extracted in the mine from Muzo (Colombia), it was offered in 1831 to William Cavendish, the 6 {{E}} duke of Devonshire by the emperor Pierre Ier of Brazil. In 1956, one found an emerald of 11.000 carats, in South Africa. The emeralds most known (and exposed) are in the following cities:

Museum of Topkapi with Istanbul (16 300 carats)
Mineralogical Museum of Moscow (11 130 carats)
Kunsthistorisches Museum of Vienna: emerald known as “ of Moctezuma ”, block of emerald covered crystal limestone which was offered to the Cortes by the Aztec sovereign ; perfume bottle (2 680 carats)
Vienna (2 200 carats)
Imperial Trésor of Iran with Teheran
British Museum with London
the American Museum off Natural History with New York presents an exceptional gem, the Patricia .

Characteristics

The emerald is made up of silicate of Aluminum and Béryllium, to which chromium is added, Vanadium and Fer. The crystalline system of emerald is hexagonal. Its hardness varies between 7,5 and 8 on the scale of hardness Mohs. The emerald is slightly dichroic (green-yellow or green-blue). Its density varies from 2,7 to 2,9. In jewelry, one cuts it mainly in “emerald” (right-angled with cut corners), in “cabochon”, “pear” or “oval”. The emerald is one of the invaluable stones most expensive. The very frequent presence of inclusions, gracefully called “frost”, is not always a handicap, because it can attest origin of the stone; Certain crystallographic originalities are very required by collectors (star with six branches, called emerald trapiche ).

The majority of emeralds are treated with oils or resins, this is why it is disadvised cleaning them by the ultrasonics.

The identification of emeralds, in particular to establish the bonds between the known layers (62 layers in 19 country) and the old stones, is done by mass spectrometry, by measuring the proportion of its Isotopes of Oxygène. The ¹⁸O/¹⁶O report/ratio varies from 7 to 25 according to the layers.

Formation

The emeralds are rare, because their formation requires exceptional geological conditions:

beryllium, component principal of beryl, is indeed especially in the magma of the earth's crust.
the chromium, the vanadium and the iron, which transform beryl into emerald, are rather located in the terrestrial coat.

Between two types of known layers, Brazil and Colombia, one notices outstanding differences:

In Brazil, the emeralds were formed, for some, there is two billion years, and others, approximately 600 million years. The crystals were solidified while mixing with a black mica, and have mineral inclusions. They often miss purity.
In Colombia, the formation goes back to 65 million years, when tectonic movements brought minerals to 300°C in contact with a sedimentary layer dating from the beginning of the Crétacé, approximately 135 million years before our era. This layer contained watery Fossile S, whose limestone shells were dissolved, and thus offered cavities which made it possible the magma to form extremely pure crystals.

Current production

The Colombia is the most important world producer (60% of the production, 6 million carats for the year 1995): mines of Chivor, Muzo, Peña Blanca and of Coscuez. Not only Colombia is champion of the quantity but also of quality. Its emeralds are generally purer than those having other sources. The national bank of Colombia has a stone collection splendid.

The distribution between the principal producer countries is the following one: Source: Statistical of the Colombian ministry for the mines and energy, given 2000 .

Symbolic system

The Emerald term, in many languages, is also source of many significances, for example English Emerald, German Smaragd and Spanish Esmeralda.

Like all the invaluable stones, the emerald, emblem of purity, inspired various symbols, monk or simply superstitious. One also lends a certain number of thaumaturgical capacities to him. Here a small list, nonexhaustive, of these various beliefs:

to improve the sight, to look after blindness: it is what the anecdote reported by Suétone in connection with the Néron emperor indicates.
to protect from the bites of ancient snake
Rome: the emerald is the color of Venus, sometimes called “stone of chastity”, which is disturbed in the event of inaccuracy. The emerald, generally, symbolizes moreover the true, sincere love.
Catholic religion: according to the minnesänger Wolfram von Eschenbach, the vase of the Graal would have been cut in an emerald fallen from the face of Lucifer when this one was driven out paradise.
the emerald is associated with May.
the Noces of emerald symbolize the 40 years of Mariage in the French folklore.
associated astrological signs: Bull, Cancer, Capricorn, Balance
In France, the emerald is appreciated because the green color has traditionally bad reputation.
It is the stone of knowledge. In the Moslem tradition, the throne on which puts back the feather and the table of Coran is of emerald.
famous the tables of emerald is laws of the esotericism, engraved on one or more emeralds by Hermes Trismégiste.

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